Abstract

Criteria are established for calculation of plasma conditions leading to ionizationinstability in plasmas generally employed in high‐power molecular laser applications. Negative ion formation is found to play an important role in causing this instability. For conditions typical of electrically excited CO2 laser mixtures, appearance of an ionizationinstability requires a negative ion concentration greater than one‐tenth that of the electrons, combined with an electrontemperature value below approximately 1.5 eV. Satisfactory agreement between theoretically determined stability boundaries and data obtained experimentally confirms the significance of fundamental collisional processes as regards ionizationinstability in CO2 laser discharges.